Process for producing lubricating oils with good low temperature hazing properties

ABSTRACT

A process for producing a finished lubricating oil with good low-temperature hazing properties from lubricating oil base stocks comprised substantially of components boiling above 800* F. and containing more than about 0.75 percent by weight sulfur by subjecting such base stock to hydrofinishing and then dewaxing the hydrofinished base stock.

United States Patent Continuation-impart of application Ser. No.

533,456, Mar. 11, 1966, now abandoned Continuation of application Ser.No. 754,475, Aug. 21, 1968, now abandoned.

PROCESS FOR PRODUCING LUBRICATING OILS WITH GOOD LOW TEMPERATURE HAZINGPROPERTIES 8 Claims, No Drawings [52] US. 208/33, 208/18, 208/87,208/264 [51] Int. Cl C10g 23/02 T501 fieIdBTSe arch .I. 208718, 23,212,213, 216,264, 87,19

[56] References Cited UNITED STATES PATENTS 2,960,458 11/1960 Beuther eta1. 208/19 3,012,963 12/1961 Archibald 208/264 2,787,582 4/1957 Watkinset al., 208/58 2,967,147 l/1961 Cole 208/87 2,984,616 5/1961 Burke etal. 208/87 3,285,848 11/1966 Donaldson et al. 208/110 3,293,173 12/1966McCall 208/264 3,340,183 9/1967 Egan 208/212 3,403,092 9/1968 Rausch208/18 Primary Examiner Herbert Levine AtlorneysMeyer N eishloss, DeaneE. Kieth and Thomas G.

Ryder PROCESS FOR PRODUCING LUBRICATING OILS WITH GOOD LOW TEMPERATUREHAZING PROPERTIES This application is a continuation of application Ser.No.

754,475 filed Aug. 21, i968 which is a continuation-in-part of varietyof treatments including deasphalting, solvent extraction, comparativelysevere hydrogen treatment sometimes called hydrotreating,solventdewaxing, acid treatment, clay contacting and more recently, mildhydrogen treatment sometimes called hydrofinishing. This last-mentionedmild hydrofinishing operation in many instances is employed in lieu ofacid treatment and clay contacting and is employed mainly in thetreatment of lubricating oil base stocks, as distinguished from crudelubricating oils, in order to remove odor and color forming materialswhich are considered to be objectionable in the final lubricating oilproduct. All of the above-mentioned operations contribute to theproduction of the final finished lubricating oil from the crudelubricating oil stock by removing undesirable constituents and/orhydrocarbon types from either the crude lubricating oil stock or theintermediate lubricating oil base stock. Generally, the prior art doesnot suggest any preferred order in which these various operations are tobe conducted other than that dictated by economic or engineeringexpediencies such as, for example, employing previously a treatingtechnique which is effective to remove materials deleterious tosubsequent treatment steps or which reduces the quantity of material tobe treated in a subsequent step, the operation of which is moreexpensive.

One of the required characteristics or properties of a finishedlubricating oil is that it be clear or bright and free from any cloud orhaze even after storage at a low temperature for a period of time. Inmany instances this desirable characteristic or property of alubricating oil can be obtained when employing any combination of one ormore of the above-mentioned treating techniques. A typical example ofthe prior art operation includes solvent dewaxing an intermediatelubricating oil base stock followed by acid and clay contacting of thedewaxed base stock. In more modern refinery operations this scheme wouldrequire solvent dewaxing of a lubricating oil base stock followed byhydrofinishing of the dewaxed material to yield the finished lubricatingoil. While this sequence of operations may in some instances be entirelysatisfactory to yield a lubricating oil having good hazing properties,it has been found that in many instances it is quite unsatisfactory.

We have discovered that when treating certain types of lubricating oilbase stocks the sequence of solvent dewaxing followed by hydrofinishingor hydrofinishing of a substantially wax-free lubricating oil base stockproduces a finished lubricating oil having poor hazing properties andthat when treating lubricating oil base stocks of this particular type,it is necessary to hydrofinish the base stock and then to subject thehydrofinished stock to a solvent dewaxing treatment.

The particular materials to which the process of our invention isapplicable can be described as comparatively high boiling, high sulfurcontent lubricating oil base stocks. By the term lubricating oil basestock is meant a fraction or group of fractions usually produced at anintermediate point in the production of a lubricating oil which lacksbut the final finishing operations, such as, for example, dewaxing,hydrofinishing, acid treatment or clay contacting, before being classedas a finished lubricating oil. Generally, such lubricating oil basestocks can be obtained from crude lubricating oil stocks, i.e.,untreated materials boiling in the general range of lubricating oils, byatmospheric and vacuum distillation followed by deasphalting, such aspropane deasphalting, solvent extraction, treatment in a Duo-Solprocess, comparatively severe hydrogen treatment, i.e., hydrotreatment,etc., or any combination of one or more of these treatments or none,depending upon the type of crude lubricating oil stock being consideredand the type of finished lubricating oil desired as product.

The lubricating oil base stocks treated in accordance with our inventionmust also have a sulfur content of at least about 0.75 percent byweight. Usually these materials will be found to have a sulfur contentof at least about 1.0 percent by weight.

Generally, the lubricating oil base stocks treated in accordance withour invention are comprised substantially of components boiling aboveabout 800 F. and contain at least about 0.75 percent by weight sulfur.Lubricating oil base stocks having a 10 percent point of about 750 toabout 775 F. or above are quite suitable. Lubricating oil base stockshaving a 10 percent point of at least about 800 F. can be treated inaccordance with the process of our invention with particularlyadvantageous results. These comparatively high-boiling lubricating oilbase stocks will generally be found to have an average molecular weightabove about 375 and usually above about 400.

The process of our invention is suitable for treatment as an entity ofthe entire spectrum of lubricating oil base stocks meeting the abovedescription as well as treatment of individual lubricating oil basestock fractions. These individual fractions generally have a range offrom about to about 120 F. between their 10 percent and 90 percentpoints and are usually considered as having a nominal spread of about F.between their 10 percent and 90 percent points. The process of ourinvention can also treat the lubricating oil base stocks described aboveeither alone or in admixture with other lubricating oil base stocks.

It is believed that the higher boiling lubricating oil base stocks whichalso have a comparatively high sulfur content initially, i.e., beforehydrofinishing, comprise certain larger sulfur containing moleculeswhich upon hydrofinishing and the removal of sulfur therefrom becomeinsoluble in or at least have a lower solubility in the remaininghydrofinished components, thereby creating the problem of hazing,particularly at low temperatures. This theory appears to be borne out bythe fact that high sulfur content lube oil base stocks having acomparatively low-boiling range do not develop hazing tendencies uponhydrofinishing nor do comparatively high-boiling lube oil base stockshaving a sufficiently low sulfur content.

Of the three major types of hydrogen-treating operations generallyassociated with the lubricating oil field, i.e., hydrocracking,hydrotreating and hydrofinishing, the hydrogen-treating operationemployed in our invention is termed hydrofinishing. Generally,hydrocracking is an extremely severe operation wherein comparativelyhigh-boiling hydrocarbons, for example, stocks containing componentsboiling above the general lubricating oil range or above l,000 F aretreated so as to effect somewhat random severing of carbon-to-carbonbonds, thereby resulting in a substantial overall reduction in molecularweight and boiling point of the treated material while concomitantlyeffecting a substantial increase in API gravity in order to producelarge quantities of materials boiling below about 600 F. and a somewhatlesser quantity of materials boiling in the lubricating oil range fromabout 600 to about 1,000 or l,l00 F. In hydrocracking, at times, theproduction of lubricating oils can be merely incidental to theproduction of gasoline and furnace oil.

The next most severe hydrogen-treating operation is termed hydrotreatingand is generally considered to be intermediate hydrocracking andhydrofinishing in its severity. Thus, hydrotreating effects asignificant amount of molecular rearrangement, while not effecting theexcessive and random breakdown of molecules effected in hydrocracking.Generally, hydrotreating is primarily employed for the saturation ofaromatics but is still sufficiently severe so as to effect, at times, asignificant reduction in boiling range of the treated material.

Finally, the least severe hydrogen-treating operation, termedhydrofinishing, operates primarily for the removal of minor quantifiesof contaminants and color-forming bodies late fractions, the inspectionsfor which are also shown in table 1.

found in lubricating oils or lubricating oil base stocks. Thus, TABLE]hydrofinishing is effective, for example, to reduce the sulfur 5 contentof the materials treated along with other contaminants Reduced MediumDlstlllate and color forming bodles but does not result ln anysignificant Cmde Ramon Almcfion B increase in APl gravity or anysignificant reduction in the boi1- ing range of the treated material.Usually any increase in AP] Grimm's/Pl 104 z gravity effected byhydroflnishing will be less than about 5 10 Viscosity, sus at API.Furthermore, at times it would even appear that the boila ing range ofthe treated material has even been increased ,2355 somewhat as indicatedby a slight increase in the ASTM 10 Sumu'q, by 8 3.8 M 2,7 1 percent andeven 30 percent points. c r o ko uu a by WI. 8.0 1.3 0.2 In thehydrofinishing operation of our process the operating g'; 80 I 793conditions employed can include a temperature from about 10 708 a 400 toabout 850 F. and preferably from about 600 to about 30 ans an ass 750F., a pressure in the range from about 800 to about 3,000 :8 :2: 2::p.s.i.g. and preferably from about 1,000 to about 2,000 90 934 9p.s.i.g., a liquid hourly space velocity in the range from about 95 967940 0.1 to about 10.0 and preferably from about 1.0 to about 4.0 volumesof lubmaung on bflse 9* P of catalyst Each of the Fractions A and B werethen subjected to furfural Per and a hydrogen cuculatlo" rate m therange from extraction at substantially the same conditions including asolabout 1,000 to about. 20,000 and Preferably from vent to oil volumeratio in the range from about 1.5 to about f 2900 f The catalyst P l'2.0 and a temperature at the tower tops of 220 F. inspection thehydrofimshmg 0136111110" ficwfdance out data for the rafiinates from thesolvent extraction of the two tron can be any of the hydrogenatingcatalysts well-known in f ti are shown in table 1 below the art such as,for example, group VI and group V111 metals, their oxides and sulfides,or mixtures thereof, either alone or TABLE H supported on a suitablecarrier. These suitable carriers generally include materials which haveextremely low- A B cracking activity, if any, and can be described ashaving a Ran-mm R'mnm cracking activity significantly below on theKellogg G 0 PI 29 0 a a cracking activity scale. Usually such materialswill have a Kel- 35 x gg g logg cracking activity of less than about 25and preferably less 100' F. 260 210 than about 20. Examples of catalystswhich we have found to 5L6 be advantageous for use in our invention arecombinations of by nickel, cobaltand molybdenum on an alumina supportsuch as, for example, a catalyst of the type described in U.S. Pat. 40The solvent extracted fraction A was then subjected to a No. 2,880,171,and a combination of nickel and tungsten on solvent dewaxing treatmentemploying a 50-50 mixture of alumina. Catalysts such as these can alsocontain a small quanmethylethylketone and toluene. The primary andsecondary tity of silica such as, for example, less than about 5 percentby solvent dilution ratios employed were 1.15 and 1.85, respecweight oreven lower. tively, and the filtration temperature employed was 14 F. Inthe solvent-dewaxing treatment of our invention we have The yield ofdewaxed oil was 80.9 percent by volume. This found that any of thewell-known solvents usually employed dewaxed oil was then subjected tohydrofinishing at a temby the art to effect dewaxing are quitesatisfactory. Generally, perature, measured at bed outlet, of 685 F., apressure of we prefer to employ a blend of methylethylketone and toluene1,755 p.s.i.g. and a liquid hourly space velocity of 2.5. in about a -50mixture as the solvent. The particular tem- As opposed to the sequenceof treatment described imperature employed in any solvent dewaxingtreatment in 5 mediately above the solvent extracted fraction B wasfirst subcordance with our invention is that which would normally bejected to hy ni g at a mp r measured t e required to provide a producthaving a desired pour point, Bullet, 0f a Pressure of 1,755 p-sg and aliqui usually about +l0 F. or lower. hourly space velocity of 2.5. Thishydrofinished oil was then in order to illustrate our invention ingreater detail, subjected to solvent dewaxing employing a 50-50 blend ofreference is made to the following examples. methylethylketone andtoluene. The operating conditions of F the dewaxing treatment includedprimary and secondary solvent dilution ratios of 1.18 and 1.58,respectively, and a filtrag t his ex intple a 5 2 pe rce nt Kuwaitreduced crude having tion temperature of 10 F. The inspection data ofcertain of the inspections shown in table 1 below was subjected to theintermediate materials and the finished products obtained vacuumdistillation to provide two comparable medium distilfrom fraction A andfraction Bare shown in table 11] below.

' w TABLE III Fraction A Fraction B Dewaxed Hydroand finished hydro-Iiydroand Dewaxed finished finished dewaxed ratfinate rafflnateraiiinato raflinate Gravity, API 26. 5 29. 3 31. 8 30. 2 Viscosity, SUSat 100 368 320 226 317 210 55. 3 53. 3 49. 5 53. 7 Viscosity index 91 95113 Pour point, F 5 +5 +100 +5 Sulfur, percent by weight 1. 25 0. 14 0.05 0.05 Carbon residue, percent by weight 0. 12 0. 06 0. 06 0. 06Distillation, vacuum, F., percent:

F. for 48 hours From the inspections shown in table I it will be notedthat the distillate fractions A and B are substantially identical andthat both fractions have a high sulfur content (2.9 percent and 2.7percent) as well as being comparatively high boiling stocks, i.e.,having a 10 percent point greater than 800F. (811 and 809 F.). Both ofthese substantially identical fractions were then subjected to the sametype solvent extraction treatment under almost identical conditions butthe raffinate from the solvent extraction of fraction A was subjected todewaxing prior to hydrofinishing, while the raffinate from the theextraction was then subjected to solvent dewaxing employing a 5050 blendof methylethylketone and toluene to provide a charge stock to thehydrofinishing unit having inspections also shown in table IV. Afterhydrofinishing, the product was t ested for hazing tendencies and theinspection data for the product together with results of the haze testare also shown in table IV. For purposes of comparison, certain of theinspections of the intermediate material as well as the final productobtained in the treatment of fraction A as described in example I arealso shown in table IV.

TABLE IV Dewaxed'and Dewaxed hydroand Dowaxed finished hydroraflmate,raflinate Dewaxed finished Fraction A Fraction A, Charge Raffinateraffinate ratfinate Example I Example I Gravity, API 26. 3 31. 4 30.030. 2 26. 5 29. 3

Viscosity, SUS at, F

l L 5.0 dll. 2 Heavy floc.

solvent extraction of fraction B was subjected to hydrofinishing and thehydrofinished material was then dewaxed. A comparison of the productinspections shown in table Ill clearly demonstrates that, although theproducts obtained from fractions A and B would appear to be almostidentical on the basis of inspections such as gravity, viscosity, pourpoint, carbon residue and distillation, quite unexpectedly the productobtained from fraction B in accordance with the process of our inventionsatisfactorily passed the haze tests at both 40 and 10 F. while theproduct obtained from fraction A was found to have formed a heavy flocafter only 24 hours at 40 F. In light of the results obtained with theproduct from fraction A in the 40 F. haze test, this fraction was notsubjected to the 10 F. haze test.

It will also be noticed from a comparison of the inspection data of thematerials charged to the hydrofinishing step with the inspection data ofthe hydrofinished materials that no substantial production of lowerboiling materials is effected in a hydrofinishing operation. Thus, intable III it is shown that the API gravity of the hydrofinished materialfrom fraction A had an API gravity only 2.8 greater than the materialcharged to the hydrofinishing step. Additionally, it will be noticedthat the ASTM 10 percent and percent points of the hydrofinishedmaterial from fraction A are somewhat higher than the correspondingdistillation points of the charge to the hydrofinishing step. Similarlyit will be noticed that the API gravity of the raffinate from fractionB, shown in table II and the charge to the hydrofinishing step, is only3 less than the API gravity of the hydrofinished raffinate shown intable III.

EXAMPLE II From the inspection data shown in table IV above for both thecharge stock and the solvent extracted raffinate it will be seen thatthe intermediate lubricating oil base stock obtained from the blendedcrude lubricating oil stock, although having a 10 percent boiling pointof about 770 F., has a sulfur content substantially below 0.75 percent.From an examination of the data shown for the hydrofinished productobtained from this material, it will be seen that no hazing problemexists. From a comparison of the results obtained in this example withthe resultant product obtained from fraction A of example I and shown inthe last two columns of table IV, it will be noted that when treating afeed stock having a very similar boiling range but having a high sulfurcontent, i.e., above about 1 percent, a serious hazing problem doesexist.

EXAMPLE III In this example a comparison is made between the finishedlubricating oils obtained from a paraffinic-type oil versus the finishedlubricating oils obtained from a naphthenic type oil. Theparaffinic-type crude employed in this example was obtained from areduced Kuwait crude of substantially the type described in example I.The Kuwait crude lubricating oil stock was separated into variousfractions and such fractions were subjected to solvent extraction,solvent dewaxing and then hydrofinishing in substantially the samemanner as described in example I. The material employed to illustratenaphthenictype oils were crude lubricating oil fractions obtained fromTia Juana crude oil. Inasmuch as the Tia Juana lubricating oil basefractions had such an extremely low pour point and a low wax contentthey were not subjected to solvent dewaxing but rather werehydrofinished directly. The following table V shows the sulfur contentof the various lubricating oil base stock fractions as well as theinspections of various hydrofinished lubricating oils obtained from thefractions of the two crudes mentioned above.

' TABLE v Lube source Kuwait Tia Juana Sulfur content of base fraction,percent by weight Medium Light Medium Heavy Light neutral Medium Distil- D istil- D istil- Fraction Neutral sidestream neutral late latelate Inspections:

Gravity, API 32. 32. 6 29. 3 27. 1 26. 3 25- 1 Vlscosity, survey:section:

100 102 108. 1 320 101 204 546 210 F- 39.5 40.0 53. 3 38.3 44. 3 58.3Viscosity index 97 96 95 36 51 53 Sulfur, percent we 0. 04 0.05 0.140.09 0. 11 0. 09 Pour point, F 0 +20 +5 60 45 Carbon-type compositionASTM 2140 percent by weight carbon atoms in:

Aromatic rings r. 3 s 6 13 12 11 Naphthenic rings. 32 24 29 32 30Parraflinic chains 65 68 65 55 58 60 Distillation, vacuum, F.corresponding to 760 mm. Hg, percent:

"i "655 "i623 "s66 Haze test appearance:

40 f Bright Bright Bright Bright 40 F. for 48 hours... do do 1 .do doAverage molecular weigh 355 360 460 320 360 445 1 Heavy 1100.

It will be first noticed that the pour points of the Tia Juana lube oilfractions are substantially lower than those of the corresponding Kuwaitlube oil fractions. lt'will also be noticed that a hazing problem existswith the medium neutral Kuwait lube oil fraction while the mediumdistillate lubricating oil fraction from the Tia Juana crude has no suchproblem. It will also be noticed that the problem of hazing does notappear to be dependent upon the portion of the crude lubricating oil,that is, light, medium or heavy, from which the fraction was obtainedbut rather appears to be dependent upon the average molecular weight ofthe material in the fraction as indicated by the boiling range of thematerial. Thus, it will be noticed that while the medium neutral Kuwaithas a hazing problem, the medium distillate Tia Juana does not, yet thefractions, either from the Kuwait or the Tia Juana crudes, which have anaverage molecular weight above about 375 to 400 or which have a 10percent point above about 800 F. do have a severe hazing tendency afterhydrofinishing.

To illustrate further that subjecting a lubricating oil fractionobtained from a comparatively high boiling, high sulfur content materialwhich demonstrates hazing tendencies after hydrofinishing to asubsequent solvent dewaxing treatment in accordance with our inventioneliminates the hazing problems, the Tia Juana heavy distillatelubricating oil fraction was subjected to dewaxing employing a 50-50blend of methylethylketone and toluene at a temperature of 5 F. Aftersuch solvent dewaxing treatment the Tia Juana heavy distillatelubricating oil showed no hazing at 40 F. after 48 hours.

We claim:

1. A process for producing a finished lubricating oil with goodlow-temperature hazing properties from a lubricating oil base stockwhich has been subjected to solvent extraction for the removal ofaromatics therefrom and which is comprised substantially of com onentsboiling above about 800 F., having a 10 percent boi mg point of a least750 F. and containing more than about 0.75 percent by weight sulfurwhich comprises subjecting such lubricating oil base stock tohydrofinishing by contacting it with hydrogen in the presence of acatalyst comprising a hydrogenating component selected from the groupconsisting of (a) nickel, cobalt and molybdenum and (b) nickel andtungsten supported on a carrier having a cracking activity on theKellogg scale of less than about 35 under hydrofinishing conditions ofspace velocity, a pressure from about 1,000 to about 2,000 p.s.i.g. anda temperature from about 600 to about 750 F. thereby effecting removalof color-forming bodies from the base stock without any significantincrease in APl gravity or significant reduction in the boiling rangeand then subjecting the hydrofinished base stock to a solvent dewaxingtreatment 2. The process of claim 1 wherein the lubricating oil basestock has a l0 percent boiling point of at least 800 F.

3. The process of claim 1 wherein the lubricating oil base stock is afraction having a range from about to about F. between its l0 percentboiling point and its 90 percent boiling point. 4 The process of claim 2wherein the lubricating oil base stock is a fraction having a range fromabout 90 to about l20 F. between its 10 percent boiling point and its 90percent boiling point.

5. The process of claim 1 wherein the lubricating oil base stockcontains more than about 1.0 percent by weight sulfur.

6. The process of claim 1 wherein the lubricating oil base stock isobtained from a paraffinic-type crude oil.

7. The process of claim 1 wherein the lubricating oil base stock isobtained from a naphthenic type crude oil.

8. The process of claim 1 wherein the catalyst carrier has a crackingactivity on the Kellogg scale ofless than about 25.

(5/69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,617,475 Dated November 2, 1971 Inventor(s) R. G. Goldthwait, J. R.Murphy, W. C. Offutt and H. C. Stauffer It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 4, Table I, Line 14, before the first column, "811" should bedeleted.

Column 8, Table V, under 760 mm.Hg, percent, across from 50, "83" shouldbe --835.

Signed and sealed this 18th day of April 1972.

(SEAL) Attest:

EDWARD I LFLETCHER,JR.

ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

2. The process of claim 1 wherein the lubricating oil base stock has a10 percent boiling point of at least 800* F.
 3. The process of claim 1wherein the lubricating oil base stock is a fraction having a range fromabout 90* to about 120* F. between its 10 percent boiling point and its90 percent boiling point.
 4. The process of claim 2 wherein thelubricating oil base stock is a fraction having a range from about 90*to about 120* F. between its 10 percent boiling point and its 90 percentboiling point.
 5. The process of claim 1 wherein the lubricating oilbase stock contains more than about 1.0 percent by weight sulfur.
 6. Theprocess of claim 1 wherein the lubricating oil base stock is obtainedfrom a paraffinic-type crude oil.
 7. The process of claim 1 wherein thelubricating oil base stock is obtained from a naphthenic type crude oil.8. The process of claim 1 wherein the catalyst carrier has a crackingactivity on the Kellogg scale of less than about 25.